1. Field of the Invention
The present invention is related to antenna for radio communications devices and more particularly, to a radio antenna for mobile computers.
2. Description of the Prior Art
Distributed data processing systems are increasingly common in the modern electronic work place. Such distributed data processing systems may include thousands of computers or workstations including main frame computers, so-called "personal" computers, and modern state-of-the-art portable or "laptop" or "notebook" or "palmtop" computers. In modern distributed data processing systems many such computers may be linked together utilizing various topologies and different types of networks including Advanced-Peer-To-Peer-Networks (APPN), Local Area Networks (LAN), Cellular, PCS, Internet, TCP/IP or various other types of networks. While in the past computer networks are generally coupled together utilizing existing telephone land line systems, or specialized wiring, modern distributed data processing systems often utilize more sophisticated means of communication.
For example, the increasing efficiency and decreasing cost of cellular communication equipment has resulted in the utilization of that technology to couple together multiple computers without the necessity of access to a telephone line outlet. This particular technology is particularly effective in combination with small, portable battery powered laptop or notebook or palmtop computer in which the necessary modern and cellular communication circuitry are miniaturized and provided in an integral fashion with the computer itself. An RF wireless communications device provides access such that the data processing terminal may be coupled to a large network utilizing RF communications technology. Thus, an operator utilizing such a computer may initiate communications and transfer data between his or her computer and a distributed data processing system without the necessity of access to either telephone lines or power lines.
The increasing utilization of such devices and the after market refitting of existing laptop or notebook or palm top type computers with such communications modules result in a problem in the efficiency of the radio frequency communication. That is, devices which are initially designed for utilization with cellular communication circuitry are constructed with internal antenna elements which are optimized for cellular communications; however, the after market refitting of a laptop or notebook or palmtop computer with a combination modern and cellular communication device often causes a problem, since such devices were not designed initially for cellular communication network linking.
The antenna devices typically utilized for cellular communication are generally composed of antenna elements, each including a radiating element which is equal in length to some fraction of the wavelength. Further, in order to enhance the efficiency of communication, these antenna elements must include elements which are separated by a minimum distance and preferably must be oriented normal to each other in space, in order to provide the necessary separation and spatial diversity. Due to the noise from the internal clock cycles and LCD display, the radiating antenna elements are usually positioned externally from the mobile computer.
The problem with a mobile computer having an external antenna is that they are awkward to pack and move. Also these antennas are easily damaged because they protrude from the mobile computer and can easily catch on persons, doorways, doors and other objects.
Also today there are many wireless communications services available to the mobile computer user. These wireless communications providers operate in different frequency bands. The mobile computer user needs to be able to have access to potentially any of the wireless services. Multiple antennas, with different electrical characteristics are typically required. This further burdens the mobile user. Thus, there is a need for an antenna to provide service in multiple frequency bands.
These unresolved problems and deficiencies are clearly felt in the art and are solved by the invention in the manner described below.